The present invention relates to improvements in closures or caps for pharmaceutical containers or bottles and more specifically relates to a closure having a removable portion detachably secured to a new and improved means for securing the removable portion to the cap.
Cap-type closures for certain types of pharmaceutical containers usually incorporate a pierceable closure member such as a disc or stopper made of rubber which seats in the discharge opening in the container and is normally sealed by an outer cap which holds the stopper in place in most instances by engaging a shoulder on the neck of the bottle. These metal overcaps in the past have usually included a detachable cover element connected to a central removable disc portion of the metallic cap which is engageable by the user to pivot the cover element relative to the cap thereby fracturing the bridge means connecting the central disc to the outer portion of the metallic overcap and thereby expose the resilient stopper so that the contents can be withdrawn by piercing it with a hypodermic syringe.
Closure assemblies of this general type are not new per se. For example, in the Ravn U.S. Pat. No. 3,071,274, the outer plastic cover element has a central depending portion which engages through an opening in the removable disc portion of the overcap to normally hold it in place. When the cover element is pivoted by the thumb of the user, the disc which is connected to the outer cap by fracturable bridges is detached thereby exposing a circular area of the stopper seated in the discharge opening in the container. This closure while it has been extremely useful in the field, nevertheless has some slight disadvantages or drawbacks which the present invention overcomes. For example, it has been found that the jagged edges produced on removing the central disc portion presents some risk of injury if contacted by the hand of the user. Additionally, the force required to remove the disc may vary depending on the particular circumferential location where the cover element is engaged. Thus, the removal force may vary from one cap to the next which are all made according to the same nominal tolerances.
Subsequently issued patents owned by the Assignee of the present application show similar type closures with variations in the manner in which the cover element is secured to a removable disc of the metallic overcap. For example, in Anderson U.S. Pat. No. 3,358,865, the central removable disc portion is likewise connected to the outer portion of the metallic cap by circumferentially spaced fracturable bridges. However, in this instance the central disc portion has a raised button which engages through a central opening in the cap and is peened over to hold it in place. This cap assembly has some of the same shortcomings of the Ravn cap structure and is somewhat expensive to manufacture and assemble.
The Labarge U.S. Pat. No. 3,369,692 shows an assembly similar to that of the Anderson U.S. Pat. No. 3,358,865. However, in this instance the overcap is metallic and the throat of the button is non-circular so that the button and disc can be removed by twisting the cover element.
Herbert et al U.S. Pat. No. 3,547,297 again shows a closure assembly similar to those described above. However, in this instance the disc portion is connected by partial scoring to the outer portion of the metallic overcap. However, the cover element is connected to the removable disc portion in much the same manner as in the Ravn U.S. Pat. No. 3,071,274. This closure likewise has been found very suitable for the purposes intended. However, again it is somewhat expensive to manufacture and assemble. Furthermore, the opening in the metallic cap to receive the depending portion of the plastic cover element defines a pathway for ingress of foreign matter which presents the possibility of contamination of the stopper. In other words, while the partial scoring eliminates a possible path for contaminants such as bacteria and the like, the opening to accommodate the cover element defines another path and thus the entire closure does not in itself provide a complete hermetic seal by reason of the opening to accommodate the cover element.
Anderson U.S. Pat. No. 3,379,326 shows a number of embodiments wherein the cover element has depending legs or a continuous skirt which engages under the central opening in the metallic cap which are fracturable when the cover element is actuated relative to the metallic cap to expose the stopper. While this arrangement eliminates the jagged edges produced on fracturing metallic bridges connecting the central disc portion to the outer cap of some of the prior assemblies, it has been found that the cap assembly is nevertheless somewhat expensive to manufacture and assemble and in some of the embodiments the removal force may not be uniform at all locations of engagement of the cover element. Furthermore, the entire closure consisting of metallic cap and cover element does not provide a complete hermetic seal.
Other closure assemblies of interest are shown in the following additional prior patents:
______________________________________ U.S. PAT. NO. INVENTOR ISSUE DATE ______________________________________ 3,193,128 Ravn July 6, 1965 3,446,170 Andersen May 27, 1969 3,587,897 Rohde June 28, 1971 ______________________________________
With the foregoing in mind, it is an object of the present invention to provide a tamper-proof closure assembly of the above type which is characterized by novel features of construction and arrangement providing greater uniformity and control over the removal force required to separate the elements of the cap to expose a portion of a stopper or the like and which is more economical to manufacture and assemble than the prior closures discussed above.
Another object is to provide a closure cap assembly which is truly tamper-evident and provides a truly hermetic seal.
To this end, the closure assembly comprises a metallic overcap having a top and a depending skirt which is adapted to be crimped under the finish on a container to hold a rubber stopper in place and a top including in the principal embodiments a removable portion defined by a bridge connection in the form of partial scoring. The outer surface of the metallic overcap which is preferably made of aluminum is coated with a thin plastic film such as polypropylene or covered with a plastic-based lacquer such as a polypropylene-based lacquer. In instances where the metallic overcap is coated with a thin plastic film or layer, the coating is preferably of a thickness of about one (1) mm and in instances where the metallic overcap is provided with a plastic base lacquer film, the film is preferably in the range of about one-tenth (0.10) mm. The closure assembly further includes a cover or button preferably made of plastic having at least a portion thereof thermally or ultrasonically bonded to the removal portion of the metallic overcap so that in use, the cover is simply engaged by the thumb of the user at a peripheral edge and pivoted to fracture the removable portion along the bridge connection and expose the stopper. The cap assembly is easy and economical to manufacture and apply to containers. Moreover, the area bonding the button to the overcap may be selectively varied to control the seating force or bonding strength between the elements thereby to provide a uniform acceptable force for removal. The components of the assembly may be assembled by first sterilizing the individual components or can be sterilized after assembly to the container, a method commonly referred to as "terminal" sterilization. In either event, the area of the stopper exposed after actuation of the cover element is in a sterile condition. Additionally, the assembled closure is truly tamper-evident and provides a truly hermetic seal between the closure assembly and the container.